Thermal contactor



Jan. l17, 1939. P, B. PARKS 2,144,120

v THERMAL CONTACTOR Filed June 19, 195e 2 sheets-sheet 1 Immun Q ill Ill.: (l.

IA i@ IIIIIIIIH menr.

orneys.

Jan. 17, 1939. P. B. PARKS THERMAL CONTACTOR A2 Sheets-sheet Filed June1 9, 1936 Ill ITIIVILIIIL if ornys.

Imre Pazzi QQ/fis' Patented Jan. 17, 1939 UNITED STATES THERMALCONTACTOR Paul B. Pai-ks, Oak Park, Ill., assignor to Vapor Car HeatingCompany, Inc., corporation of New York Application June 19,

9 Claims.

This invention relates to Certain new and useful improvements in athermal contactor; more particularly to an improved re-closing circuitbreaker adapted to be operated by a thermostatic element to temporarilybreak a circuit when the current flowing in this circuit becomesexcessive, or flows for too long a period of time.

As is Well known, one of the principal requirements or any circuitbreaker is to provide for a sudden, complete and decisive breaking ofthe circuit so as to minimize injurious sparking at the electriccontacts when these contacts are separated. Usually some form ofsnap-Spring mechanism is provided to suddenly separate the l5 contacts.However, if this snap-mechanism is -operated by a slowly movingthermostatic member there will usually be a dead-center position of thesnap-spring mechanism, just before the quick actuating movement takesplace, when substantially no pressure is exerted on the contact memberswith the result that these contacts may tend to slightly separate orchatter thereby producing injurious sparking. To avoid this it has beenproposed to add a magnetic detent to hold the contacts together whilethe spring mechanism is being moved over dead-center, but even thisdevice has not been entirely effective since there is a position Wherethe holdingpower of the magnet is just oiiset by the weakened spring- 3@action so that chattering may occur.

According to the present improvement the movable contact member ismounted on a carrier that is not directly connected with the snapspringactuating mechanism. A magnetic detent is provided for holding thecarrier in one extreme position with the contacts engaged. v Thesnapspring mechanism has freedom of movement with respect to thecarrier, but after this spring-mechanism has passed its dead-centerposition in either direction it Will forcibly engage a portion of thecarrier so as to impact the same and move the carrier quickly to itsother extreme position.

As a result the electric contacts Will be held firmly together by themagnetic detent until the snapspring mechanism has started its movementin the contact-separating direction and has gained suiiicient speed andmomentum to effect a quick /and decisive separation of the contacts.

The principal object of this invention is to pro- Vide a thermalcontacter of the type briefly described hereinabove and disclosed morein detail in the specifications which follow.

Another object is to provide a circuit-breaker comprising a snap-springmechanism having lost lmotion connection with the movable switch contactin combination with a magnetic detentfor holding the contacts inengagement while the spring mechanism is reversing its direction ofmovement. 6o 4Another object is to provide an improved form Chicago,Ill., a

1936, SerialNo. 86,138 (Cl. 200-122) of thermally actuated re-closingcircuit breaker.

Other objects and advantages of this invention will be more apparentfrom the following detailed description of certain approved forms ofmechanism constructed and operating according to the principles of thisinvention.

In the accompanying drawings:

Fig. 1 is a vertical section taken substantially on the line l-lcf Fig.3, and showing the ins ternal mechanism in top plan view.

Fig. 2 is a vertical section taken substantially on the line 2 2 of Fig.3.

Fig. 3 is a vertical section taken substantially on the line 3-3 of Fig.1 and showing the internal mechanism in side elevation with the contactsseparated.

Fig. 4 is a central vertical section taken substantially on the lineli--fl of Fig. l, and showing the contacts engaged or in circuit-closingposition.

Fig. 5 is a rea-r elevcticn partially broken away.

Fig. 6 is a transve e section taken substantially on the iine or Fig. land showing the internal mechanism in end elevation as looking frombelow at Fig. l.

Fig. 'l is a vertical section, similar to Fig. 2, but showing a modiiiedform of snap-spring operating mechanism,

Fig.. 8 is a vertical section taken substantially on the line oi Fig. 7.

Referring iirst to the form of the invention shown in Figs. l to 6inclusive, the operating parts of this device are carried by a baseblock l of insulating material, which in turn is carried through aninsulating block 2 by a metallic cross bar 3 adapted to be securedagainst a wall or panel by screws or other devices inserted through theholes il.

A pair of similar spaced apart electric contacts 5 and' are mounted. inthe lower portion of block l, these contact members extending throughthe block so that the rear portions thereof may serve as binding postsat the back of the block as indicated at 5 and in Fig. 5. A. pair ofmovable contacts 'l and B, adapted to engage respectively with the xedcontacts 5 and 6, are mounted on a metallic carrier 9 which serves toelectrically connect the contacts "l and 8. As a consequence, when thecontacts 'l and are moved into engagement respectively with the contacts5 and 6, the carrier and movable contacts will serve to bridge orcomplete a circuit between the fixed contacts 5 and 6. The carrier ismounted loosely at its upper end as indicated at lil on the supportingblock l so that the contacts 'i and 3 will be held in proper alignmentwith the xed contacts E and 6 but the carrier is free to move toward orfrom the supporting block l in a pendulum-like manner so as to make orbreak the connections between the contact members. A permanent horseshoemagnet II is mounted in a suitable recess formed in the back of block I,and post extensions I2 project forwardly through the block I from therespective poles of the magnet so as to attract an intermediate portionI3 of carrier 9 which serves as an armature for the magnet. When theparts are moved to the circuit making position shown in Fig. 4 thevarmature I3 is brought adjacent the poles I2 of the magnet so that themagnet tends-to strongly attract the carrier and hold the respectivepairs of contacts 5, 1 and 6, 8 in rm engagement with one another.However, this magnetic attraction is not so strong but what it may bebroken by a suicient force applied to carrier 9 in the oppositedirection, as hereinafter described. The lower end of carrier 9 isextended outwardly at I4 and then upwardly at I5 so as to provide asuitable space or gap between the member I5 and the opposing portion I6of thev carrier on which the contacts 1 and 8 are mounted. The free endportion of the snap-spring mechanism operateswithin this gap as will behereinafter described.

In order to limit movement .of the carrier 9 in the contact-separatingor circuit-opening direction, the portion I5 of the carrier is adaptedto engage a stop plate I1 carried by a pair of posts I8 projectingforwardly from base block I. -The lower end of a thermostatic bar I9 isanchored at I 9' .on this same stop plate I1. This thermostatic memberI9 is preferably in the form 0f a bi-metallic bar adapted to warp orbend in one direction when heated. The bar I9 is wrapped with a heatingcoil of high resistance material. One end of this heating coil 28 isconnected through ilexible conductor 2| with a binding post 22, and theother end of the coil is connected through ilexible conductor 23 with asecond binding post 24. These binding posts 22 and 2d extend through tothe back of the supporting blockvl as indicated in Fig. 5 at 22' and 24.Binding post 22' is connected through the conductor bar 25 with thefixed contact member 5. The other fixed contact member 6 is connected atthe back of the assembly by conductor bar 26 with a third binding post21. The outside circuit wires 28 and 29 are connected respectively withthe binding posts A24 and 21. It will thus be seen that when theassembly is in circuit-closing position, a circuit will be completedthrough the contactor as follows: From circuit wire 28 through bindingpost 24, conductor 23, heating coil 20, conductor 2I, binding post 22,conductor bar 25, xed contact 5, movable contact 1, carrier 9, movablecontact 8, xed contact 6, conductor bar 26, binding post 21 and theother circuit wire 29.

The thermostatic bar I9 is adapted to operate the snap-spring mechanismVwhich in turn moves the contact carrier 9. In the forms shown in Figs.1 to 6, this snap-spring assembly comprises a.long at leaf-spring 38 theupper end of which is connected at 3| with the free or movable end ofthrmostatic bar I9. The lower end of leaf-spring 30 is connected throughcrossbar 32 with the lower ends of a, pair of similar bowed springs 33and 33 which are shorter than the main leaf-spring 30. If desired, thesprings 30, 33 and 33 may all be stamped from the same sheet of springmetal, that is they may all be integrally connected atA their lowerends. The upper ends of the springs 33 and 33 bear against a pair ofsimilar fulcrum posts or bars 34 and .34 which are mounted on ba'seblock I. The bowed springs 33 and 33' are under longitudinalcompression, that is tend to force the spring assembly downwardly. As aresult, if the main central leaf-spring is moved rearwardly or forwardlybeyond the fulcrum point or deadcenter position, the tendency of thesprings 33 and 33 to expand or straighten out will tend to swing or snapthe lower end of leaf-spring 38 further in that same direction.J Whenthe spring assembly is snapped toward the base plate I, as shown inFigs. 4 and 6, the stud 35 positioned centrally on the rearface of crossbar 32 engages the central lower portion of member I6 of carrier 9 andforces the contacts 1 and 8 into engagement with the xed contacts 5 and6. This central stud 35 serves as an equalizing member to distribute thepressure between the two movable contacts 1 and 8. When the springassembly isv snapped vto the other side of its dead-center position, thecross-bar 32 will swing across the gap between members I6 and I5 andforcibly strike the portion I5 of the carrier and continued movement ofthe lower end of the spring assembly will swing the carrier in thisoutward 'direction until member I5 engages the stop plate I1. Thisposition of the parts is shown in Fig. 3.

The entire operating assembly is housed Within a sheet metal casing 36which engages at its inner edge in a groove 31 formed around the outeredge of base plate I. The casing 36 is held in place by a screw 38engaging in an insulating bar 39 secured across the outer ends of thepost extensions I8.

In describing the operation| of this device, let us assume that it istobe used in a circuit that is normally closed only for short intervals oftime. The current in this circuit is of such strength that if it shouldcontinue to iiow for an abnormally long time it might burn out parts ofthe apparatus in this circuit.

indicated in Fig. 4. That is the movable contacts 'I and 8 are closedagainst the xed contacts 5 and.l 6. Now when the circuit is completed atNormally the circuit will berclosed through the contactor as some otherpoint, a rather heavy current will iiow through the heating coil 20 soas to raise the temperature of the thermostatic bar I9 which will startto warp outwardly, that is away from base plate I. If the `iow of thiscurrent persists for a longer time than is normally desirable, thethermostatic bar I`9 will warp outwardly suflicient to move the upperend of a leaf spring 30 past the dead-center position. As the springassembly reaches dead-center, it will be apparent that the lower end ofthe spring assembly no longer exerts any pressure against the contactcarrier 9, but the carrier will still be drawn toward the supportingblock I by the attraction of `magnet II so that the movable contactswill still be held rmly against the viixed contacts. 'Ihis contactengagement will still be maintained after the spring` assembly starts tomove in an outward direction. However, as the lower end of the springassembly gains momentum and is snapped forcibly outward or away from thesupporting plate I, the cross bar 32 will hit the portion I5 of thecarrier with'a hammer-blow and suddenly move the carrier outwardlyagainst the xed stop I1. The fixed and movable contacts will thus besuddenly andV decisively separated, and sparking therebetween will bereduced to a minimum.

It will now be seen that if the movable contacts were carried directlyby the snap-spring mechanism, or the snap-spring mechanism wereconnected directly with the .contact carrier 9 there would be a pointwhere the forces tending to hold the fixed and movable contacts.inengagement would be substantially neutralized by opposing iorces andthe contacts would have a tendency to chatter. However, With the presentconstruction the contacts are held firmly together by the magneticdetent until separated by a quick hammer-blow as the movable end of thesnap-switch mechanism moves suddenly into engagement with a portion ofthe carrier.

While one particular form of snap-spring mechanism has been described,it is to be understood that there are-numerous forms of such springmechanism that might be used, the only essential being that thismechanism be adapted for slow movement to and slightly past deadcenterposition whereupon it will snap suddenly to an extreme position in thisdirection. Another form of spring-mechanism is shown, by way of example,in Figs. 7 and 8. A U-shaped swinging plate 40 is pivotcd at its lowerend 4| on a xed support, and the upwardly projecting arms 42 arepivotally connected at 43 with the downwardly projecting arms 44 ofanother U-shaped plate 45. A spring 4B is connected under tension in thespace between the pairs of arms 42 and 44 so that when this assembly isbuckled in one direction or the other from a straight alignment of thetwo plates 42 and 45, the tendency of the spring will be to snap the twoplates toward one another. The upper end of plate 45 carries the crossbar41 on which is mounted the central stud 35 which is adapted to engagependulumlike carrier 9' pivoted at its lower end on which carrier aremounted the movable contacts 1 and 8,

all as in the rst described form of the inven form of the invention.Other parts not here referred to may be assumed to be essentially thesame as those already described. As shown in Fig. 8, the snap-springmechanism has been centrally buckled or bowed away from the supportingblock I so that the contraction of the' spring 46 has swung the upperend of plate 45 toward the supporting block so as to engage the carrierand move the contacts 1 and `Ii into engagernent with the fixed contacts5 and 6. As current ows through the circuit of heating coil 20 thethermostatic bar 5| will be warped toward the supporting block I so asto straighten out or align the two swinging plates 42 and 45. As theassembly reaches a dead-center position the pressure of stud 35 on thecontact carrier 9 will be released but magnet II will act to hold the.carrier toward the supporting block and hold the movable contacts inengagement with the xed contacts. As the swinging plates 42 and 45 passa ldead-center position, the upper end of plate 45 will be suddenlysnapped outwardly so that bar 41 will engage with portion I5 of thecontact carrier 9' and suddenly swing the carrier outwardly against xedstop 48 and thus break the circuit. This action need not be furtherdescribed since it is essentially the same in all respects as that ofthe first described form of the invention.

I claim:

1. In an electric contactor, xed and movable contacts, a carrier onwhich the movable contact is mounted, the carrier being movable betweentwo extreme positions in one of which the contacts are engaged tocomplete a circuit and in the otherof which the contacts are separatedto break the circuit, a portion of the carrier serving as an armature, amagnet positioned to attract the armature and tend to hold the contactsin engagement with one another, a snap-spring mechanism having twoopposite movable end portions and an intermediate fulcrumed portion, axed fulcrum member engaged by this intermediate portion of thesnap-spring mechanism, one movable end portion being adapted to snap toone or the other of two opposite positions when the spring mechanism ismoved over a deadcenter position and having limited freedom of movementwith respect to the carrier but adapted to engage the carrier after thesnap-spring mechanism has passed a substantial distance beyond itsdead-center position in either direction and thereafter shift thecarrier from one to the other of its extreme positions, a thermostaticmember operatively connected with the other movable end portion of thesnap-spring mechanism and adapted to move this mechanism past itsdead-center position, and an electric heater for the thermostaticmember, said heater being connected in the circuit controlled by thecontacts.

2. In an electric contacter, xed and movable contacts, a carrier onwhich the movable contact is mounted, the carrier being movable betweentwo extreme'positions in one of which the contacts are engaged tocomplete a circuit and in the other of which the contacts are separatedto break the circuit, a portion of the carrier serving as an armature, amagnet positioned to attract the armature and tend to hold the contactsin engagement with one another, a snap-spring mechanism having twoopposite lmovable end portions and an intermediate fulcrumed portion, axed fulcrum member engaged by this intermediate portion of thesnap-spring mechanism, one movable end portion being adapted to snap toone or the other of two opposite positions when the spring mechanism ismoved over a deadcenter position and having limited freedom of movementwith respect to the carrier but adapted to engage the carrier after thesnap-spring mechanism has passed a substantial distance beyond itsdead-center position in either direction and thereafter shift thecarrier from one to the other of its extreme positions, a thermostaticbar fixed at one end and having its free end portion connected with theother movable end portion of the snap switch mechanism so as to movethis mechanism past its dead-center position as the bar is warped in onedirection or the other, and an electric heating coil associated with thebar and connected in the circuit controlled by the contacts.

3. In an electric contactar, fixed and movable contacts, a carrier onwhich 'the movable contact is mounted, the carrier being movable betweentwo extreme positions in one of which the contacts are engaged tocomplete a circuit and in the other of which the contacts are separatedto break the circuit, means normally tending to hold the carrier in thefirst extreme position with the contacts in engagement with one another,a snapspring mechanism having two opposite movable end portions and anintermediate fulcrumed portion, a fixed fulcrum member engaged by thisintermediate portion of the snap-spring mechanism, one movable endportion being adapted to snap to one or the other of two oppositepositions when the spring mechanism is moved over a dead-center positionand having limited freedom of movement with respect to the carrier butadapted to engage the carrier after the snap-spring mechanism has passeda substantial distance beyond its dead-center. position in eitherdirection and thereafter shift the carrier from one to the other of itsextreme positions, a thermostatic member operatively connected with theother movable end portion of the snapspring mechanism and adapted tomove this mechanism past its dead-center position, and an electricheater for the thermostatic member said heater being connected in thecircuit controlled by the contacts. 4. In an electric contacter, Xed andmovable contacts, a magnetic detent normally tending to hold thecontacts in engagement to complete a circuit, a snap-spring mechanismhaving two opposite movable end portions and an intermediate fulcrumedportion, a fixed fulcrum member engaged by this intermediate portion ofthe snap-springmechanism, one movable end `portion being-adapted to snapto one or the other of two opposite positions when the spring mechanismis moved over a dead-center position and having a lost-motion connectionwith one of the contacts whereby the snap-spring mechanism may be moveda substantial distance beyond its dead-center position and willthereafter engage and move the movable contact to break the circuit,althermostatic member operatively connected with the other movable endportion of the snap-spring mechanism and adapted to move this mechanismpast its dead-center position, and an electric heater for thethermostatic member said heater being connected in the circuitcontrolled by the contacts.

5. A snap switch comprising in combination a tension member and anadjacent compression member each operatively mounted at one end and 4"connectedtogether at their opposite ends which are free to move,alloosely mounted pendulumlike member having a U-shaped end portionforming a pair of stops between which said conr nected end part moves,at least one of said first o two members comprising spring means, saidcompression member being mounted operatively at a point whereby it has adiierent radius of action than said tension member, said stops beingmovable with -said connected end part when said connected end partstrikes a stop after leaving the opposite stop, at least one of saidstops having electrical contact means thereon associated with stationaryelectrical contact means, the arrange- 60 ment being such thatelectrical'contact at said 'stationary electrical contact means is madeor broken as said end portion snaps from one stop to the other. i

6. A snap switch comprising in combination 5 an elongated memberoperatively mounted at one end with the opposite end free to move, a.

loosely mounted movable member, stops formed by spaced apart portions ofsaid loosely mounted member between which said free end moves, said 0switch being so constructed that said free end moves from one stop tothe other with a snap action, said stops being movable with said freeend when said free end strikes astop after leaving the opposite stop, atleast one of said stops having electrical contact means thereonassociated with stationary electrical contact means, the arrangementbeing such that the electrical contact at said stationary electricalcontact means is made or broken as said free end portion snaps from onestop to the other.

7. A snap switch comprising, in combination a member which moves with asnap action,' a pendulum-like member comprising movable stops betweenwhich said snap action member moves, said switch being so constructedand arranged that said stops move with said snap action member when saidmember strikes a stop after leaving the opposite stop, at least one ofsaid stops having electrical contact means thereon associated withstationary electrical contact means, the arrangement being such that theelecsnaps from one stop to the other.

8. A snap switch comprising, in combination, an elongated memberoperatively mounted at one end with the opposite end free to move, aloosely mounted magnetic pendulum-like member having' a U-shapedportion, stops formed by the inner surfaces of said U-shaped portionbetween which the free end of said rst member moves, said switch beingso constructed that said free end moves from one stop to the other witha snap action, an electrical contact on the exterior side of one leg ofsaid U-shaped end portion and pressingagainst a stationary electricalcontact, a magnet contiguous to and in such relation to saidpendulum-like member as to tendvto hold said two contacts together, saidfree end portion pressing against the electrical contact leg of saidU-shaped part when said two contacts are in contact, said switch beingso constructed and arranged that when said free end strikes the oppositeleg or stop the pull of said magnet on said pendulum-like member isovercome and said contacts are separated, thereby breaking theelectrical circuit controlled thereby. v

9. A snap -switch comprising, in combination,

an elongated member operatively mounted at one end with the opposite endfree to move, a loosely mounted magnetic pendulum-like meniber havingspaced apart portions, stops formed by the spaced apart portions of saidpendulumlike member between which the free end of said rst member moves,said switch being so constructed that said free end moves from one stopto the other with a snap action, an electrical contact on the exteriorside of one part of said spaced-apart portion and pressing against astationary electrical contact, magnetic means tending to hold said twocontacts together, said free end portion pressing against the electricalcontact portion of said pendulum-like part when said two contacts are incontact, said switch being so constructed and arranged that when saidfree end strikes the opposite stop-or the opposite portion of'saidspaced-apart section said magnetic attraction is overcome and saidcontacts are separated, thereby breaking the electrical circuitcontrolled thereby. r

PAUL B. PARKS.

@que

